As I Understand the Split X2 keyboard doesn't respond or charge,
No worries, as I'll be glad to help you, that said, I'll need a few more details to dissect your concern & provide an accurate solution:
Did you check with an alternate keyboard is that works?
Do you have any alternate adapter you can charge with?
It would be easy to identify the issue by narrowing it further down to the basics,
I recommend you try the steps and reply with the results.
If you've checked with an alternate keyboard (same model) and an alternate power cord and yet the issue persists, Please Contact HP as this would be determined as a hardware malfunction and you can get yourself replacement parts that should resolve the issue: